The biostatistical core will support the efforts of all 4 projects through study design, statistical analysis and preparation of manuscripts. The core will be lead by Dr. Reilly, and he will be assisted by an research assistant with experience in Biostatistics. This core will perform power analysis and participate in protocol design to ensure that the data that is collected will allow evaluation of project hypotheses. In addition, this core will supervise data entry procedures and regularly communicate with project leaders regarding the accumulation of data to ensure the highest quality data. This core will be responsible for all data analysis and will participate in the drafting of manuscripts that involve statistical analysis of the data. The core leader, Dr. Reilly, has worked with several of the project leaders previously and has extensive experience with the spatial and longitudinal data that will be generated by these investigations.